The present invention relates to an image forming apparatus to which a double-sided printing unit can be detachably mounted and in which a medium jammed therein can be easily removed.
There has been known an image forming apparatus configured such that a double-sided printing unit having a double-sided image forming function can be mounted to a side part of a main body of the image forming apparatus in place of a transporting unit dedicated for forming a single-sided image so as to selectively provide a double-sided image forming function in accordance with user's desire (see, e.g., JP-A-2002-116591). Of the image forming apparatus, the transporting unit has rollers that constitute a paper-transporting path for forming an image on a single face of a medium.
In addition, each of the double-sided printing unit and the transporting unit has a manual paper-feeding unit.
In the above-described related-art image forming apparatus, when the double-sided image forming function is required by a user, the double-sided printing unit is mounted to the side part of the main body in place of the transporting unit.
Therefore, when the double-sided printing unit is mounted, the transporting unit is no use.
In addition to having the rollers forming the paper-transporting path for formation of an image on a single side, the transporting unit has the manual paper-feeding unit. Accordingly, the manual paper-feeding unit goes to great waste.
An image forming apparatus has, e.g., a fixing unit for fixing a toner image on a medium. The fixing unit has a first member and a second member which can nip a medium therebetween, and a pressing member for pressing the second member against the first member; and fixes a toner image on the medium nipped between the first member and the second member that is pressed by the pressing member.
In the image forming apparatus, during the course of a medium passing between the first member and the second member, a medium jam sometimes occurs. For the purpose of removing the thus-jammed medium, a door cover is provided in the image forming apparatus. Accordingly, a user, or the like, opens the door cover and removes the medium jammed in the image forming apparatus.
However, even when the door cover is opened by a user, in a condition where the second member is pressed against the first member by the pressing member, since the medium is nipped between the first member and the second member, removal of the medium jammed in the image forming apparatus encounters difficulty. To this end, an image forming apparatus has a connecting member for connecting the door cover and the fixing unit, and releasing a pressure exerted by the pressing member in association with opening motion of the door cover. By virtue of the configuration, when the door cover is opened, the pressure exerted on the second member by the pressing member is released, thereby facilitating removal of the jammed medium. (see, e.g., JP-A-2003-287973)
Meanwhile, the pressure exerted on the second member by the pressing member is desirably released before the door cover becomes fully opened. The reason therefor is that a user, or the like, sometimes attempts to remove a jammed medium in a state where the door cover is half-open before being fully opened.
Meanwhile, when the connecting member releases the pressure on the second member exerted by the pressing member, the pressing force of the pressing member serves as a resistance. Thus, the resistance is applied in a direction that opens the door cover, thereby preventing the door cover from bursting open. However, when the pressure is released before the door cover becomes fully open, the resistance against the opening motion of the door cover no longer acts after the release of the pressure. As a result, the door cover sometimes bursts open. When the door cover bursts open, a large impact is imparted on the image forming apparatus, which may adversely affect other components, or the like. Therefore, the impact imparted on the image forming apparatus upon opening of the door cover is desirably suppressed.